Police departments from Florida to Arizona are converting their squad cars to the old color scheme made famous by the TV police drama that aired from 1968 to 1975. The reasons: tradition and better visibility.

In Mesa, Ariz., the police department's 287 marked Ford Crown Victoria cruisers — white with a blue decal on the doors — will be switched to black-and-whites over the next six years.

"Studies have shown that cars with alternating light and dark colors are more visible in low light or high illumination," says department spokesman Chuck Trapani. He says many civilian cars are white in a hot-weather region. Having cruisers painted black on the hoods, trunks and fenders will make them more visible, both to other drivers and the department's helicopter.

"It's also a morale thing," Trapani says. "We did a survey in the department, and a majority of the police officers wanted to go with black and white."

In Monroe, Wis., a city of 11,000 people in the southern part of the state, the police department switched its four marked cruisers in March, returning to the black-and-white scheme the city used in the late 1990s before going with white cars with color striping.

"The officers like it because it's retro," Chief Fred Kelley says. "There's also some practicality. There's a bit more visibility. In Wisconsin, where the snow flies, we found white cars blend in with the snow."

To keep costs down, Monroe bought black Chevy Impalas and had a body shop paint the doors and roof white, for about $800 per vehicle.

Though many police departments cite visibility as a reason for the switch, an expert in emergency vehicles and color visibility says the black-and-white paint job isn't the optimum scheme.

"If you two-tone a vehicle, you camouflage it more than if you use a single car color," says Stephen Solomon, an Owego, N.Y., optometrist and member of New York state's Department of Motor Vehicles medical advisory board. "In a municipal setting, the background is straight lines, and when you two-tone a vehicle, you break down the ability to be able to see it in silhouette."

Solomon says the way to make cars more visible is to use lots of fluorescent, reflective tape. The best color is lime-yellow, frequently used on firetrucks, he says.

The National Safety Council, a non-profit organization that promotes health and safety, recommends to its business members that their fleet cars be painted in light colors with contrasting company logos for better visibility.

Officers like the black-and-whites, says Bill Sager, police chief in Port Richey, Fla., whose department is converting its nine-car fleet. He envisioned a silver color but left the decision up to his officers, who opted for tradition.

"When one gets behind you, you can very easily pick it out as a cop car," Sager says. "I didn't care for the black-and-white scheme at first, but once you see them, they really grow on you."